Pulsating-current generator



(No Model.)

H. N. MARVIN. PULSATING CURRENT GENERATOR.

Patented Aug. 2, 1892.

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Unrrnn STATES PATENT QFFICEQ HARRY N. MARVIN, OF SOHENECTADY, NE\V YORK.

PU LSATlNG-CURRENT GENERATOR.

SPECIFICATION forming part of Letters Patent No. 479,951, dated August 2, 1892.

Application filed December 3, 1891. Serial No. 413,885. (No model.)

To aZZ whom, it may concern:

Be it known that I, HARRY N. MARVIN, a citizen of the United States, residingat Schenectady, in the county of Schenectady and State of-New York, have invented certain new and useful Improvements in Pulsating Current Generators for Electric Percussion- Drills and other Purposes, of which the following is a specification, reference being had to the drawings accompanying and forming a part of the same.

This invention is applicable to and is primarily designed for use in connection with reciprocating electromagnetic drills or similar tools which require for their operation currents of rising and falling potential directed alternately through the two en ergizin g-ci rcu its that effect the movements of the core.

The invention is, however, applicable to any system involving the employment of pulsating currents, and particularly those in which there is occasion for usingcurrents ofcomparatively low frequency.

My invention admits of certain useful results not heretofore attainable with the same economy and case, such results being in the main the regulation of the period of pulsations without reference to the speed of rotation of the prime generator and the regulation of the voltage of the operating-current without variation of the electro-niotive force primarily set up by the generator. These objects I accomplish by means of the particular devices illustrated in the drawings and described in detail herein, and which both in respect to their construction and principle of operation I believe to be original with me.

Figure 1 is a perspective view of the improvements constituting my invention. Fig. 2 is a sectional View of the same with a diagram of circuit connections.

I employ as the generator any ordinary continuous-eurrent dynamo having a continuously-wound armature of the Gramme or Siemens type. I have shown only a portion of the armature A of this machine, as the construction is familiar to any one skilled in the purpose, or they may be used to deliver current to the armature to produce its rotation, or they may be omitted altogether.

Surrounding the commutator is a cylinder or cylindrical or other support of any suitable kind that is capable of being rotated around and independently of the commu tator. This support I have shown in the drawings as a cylindrical frame carried by a spider E, that is mounted on the shaft outside the connnutator and provided with a pulley by which it may be rotated in either direction around said shaft and commutator. This support carries what for convenience I construct as two metal bearings or collectingrings F G. The ring G is continuous and is insulated from the frame or support. The ring h is divided into two insulated segments or half-rings/"f, the latter of which may be of other material than metal, if so preferred.

Carried by the cylindrical supportor frame are two bearing-blocks II II, of metal or carbon, constituting brushes of any suitable kind, that bear upon the commutator and take off current therefrom. One of these blocks or brushes ll is in electrical connection with the half-ringji The other is electrically connected with the continuous ring G. These brushes may be carried by the respective rings with which they are connected or attached to any other part of the rotary frame, but insulated, except as to the connections named.

Two collecting-brushes L L, placed diametrically opposite, bear upon the half-rings ff alternately, and a single brush M bears upon the continuous ring G.

The drill is shown as consisting of a magnetic core N, to which the tool is connected, and a sectional coil ortwo ei'iergizing-coils or solenoids O I, surrounding the same.

The middle point or connection of the two drill-coils is connected by a conductor R with the brush M, that takes current from the com plete ring G, and the free ends or terminals of the two coils are connected by wires S T with the brushes L L, respectively.

The operation of this system is as follows: If while the machine or main generator is in operation the brushes or bearing-blocks be turned so as to bear upon two points on the tween said brushes H H varies according to their position on the commutator with reference to the line of commutation and is at a maximum when they are turned so as to lie in such line. Therefore if the brushes H H be revolved continuously the potential be tween them will rise and fall between minimum and maximum and the half-ring f and continuous ring G become the terminals of a source of pulsating current of a period or frequency determined entirely by the rate of rotation ofthe rings and brushes about the commutator. Inasmuch as the brush M is always in contact with ring G and brushes L L alternately in contact with half-rings ff during half of the revolution of the rings, each drill-coil will receive in alternation a pulsation or impulse of current of rising and falling potential and of any degree of frequency that may be found most efficient, while at the same time the generator may be driven at any speed which secures the greatest efficiency. I provide, also, for taking off for the drill or drills a current of any voltage below the maximum voltage of the generator by making the brushes or blocks H H adjustable relatively to each other. The voltage of these brushes H H will depend upon their angular displacement, so that if the voltage of the main brushes D is five hundred volts and brushes H H are ninety degrees displaced or separated from each other the maximum voltage developed between them as they rotate about the commutator would only be two hundred and fifty volts, more or less, depending, of course, upon the distribution of the field of force about the armature. By increasing or decreasing the angular displacement of the two brushes H H the voltage may be adjusted, as desired. IVhen brushes H and H are about equidistant from either brush D, the voltage betwen them becomes 9121, so that by rotating the support or structure carrying the brushes and rings and properly adjusting the position of brushes H H a pulsating electro-motive force of any intensity equal to or below the 1naximum which the generator is capable of developing and of any frequency may be obtained.

One or both of the brushes H H for the above purpose are made detachable from their support, whereby their positions may be changed. This I have illustrated by showing brush H as provided with a plate that 1s secured by a set-screw to the end or edge of the cylinder.

I am aware that pulsating currents have been taken from continuous-current-machine commutators by brushes bearing on the commutator and rotated with respect thereto, and this I do not claim, broadly; but

What I claim as of my invention is- 1. The combination, with the commutator of a continuous-current armature, of bearing blocks or brushes capable of rotating about the commutator and means for establishing connection alternately between said brushes and the two coils or circuits of a drill or drill system, as set forth.

2. The combination, with the commutator of a continuous-current armature, of two rotary brushes, contact-terminals in electrical connection with the two rotary brushes, respectively, and collecting -brushes adapted for connection with the conductors of two drill-circuits and taking the currents from the said terminals alternately, as herein set forth.

3. The combination, with the commutator of a continuous-current armature, of rotating brushes and means for connecting the same alternately with two working circuits, said brushes being capable of adjustment or varying angular displacement, as and for the purpose set forth.

4. The combination, with the commutator of a continuous-current armature, of an independently rotatable frame or structure surrounding the commutator, brushes carried thereby and bearing on the commutator, a metallic continuous ring and a metallic segment on the frame, to which the said brushes are respectively connected, a single brush bearing on the continuous ring, and two brushes bearing alternately on the half-ring, the said brushes forming the terminals of two working circuits, as herein described.

5. The combination, with the rotating commutator of a continuous-current armature, of rotating collecting brushes connected or adapted for connection with a working or translating device, said brushes being capable of adjustment or varying angular displacement with respect to each other and the line of commutation, as and for the purpose set forth.

HARRY N. MARVIN.

IVitnesses:

RoBr. F. GAYLoRD, PARKER W. PAGE. 

